Thin plate formation method, thin plate and suspension correction apparatus, and correction method

ABSTRACT

Laser beam irradiation areas are provided in a load curve portion and an angle adjustment portion of a suspension. The laser beam irradiation areas are oriented in a direction in which the suspension is to be bent. A laser beam having a predetermined length and a predetermined shape is irradiated onto each laser beam irradiation area.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a technology for correcting load and anangle of a suspension that supports a magnetic head slider of a harddisk drive.

2. Description of the Related Art

Recording densities of the hard disk drives have improved remarkably. Asa result, the suspensions that supports the magnetic head in the harddisk drives needs to be manufactured with more precision than everbefore.

The magnetic head is pressed against the magnetic disk while themagnetic disk is rotating. As a result, the magnetic head fliesaerodynamically at a predetermined distance from the disk. The load, thefine roll angle, and the pitch angle of the suspension greatly affectthe flying of the magnetic head. The load, the roll angle, and the pitchangle of each suspension are corrected during the manufacturing process.

A conventional approach to correct the load, the roll angle, and thepitch angle of the suspension is to correct them mechanically.Precisely, an outrigger of a flexure that holds the magnetic head isheld mechanically, for example, by tool, and the outrigger is bent ortwist in an appropriate direction. However, this approach requires atool having an appropriate shape to hold the outrigger and a mechanismto move the tool. Thus, this approach is costly and troublesome.

Another conventional approach to correct the load, the roll angle, andthe pitch angle of the suspension is to thermally deform the suspensionby irradiating a laser beam to the suspension. This technique isdisclosed, for example, in Japanese Patent Application Laid-openPublication No. 2000-339894 and Japanese Patent Application Laid-openPublication No. H7-77063.

According to the technique disclosed in Japanese Patent ApplicationLaid-open Publication No. 2000-339894, the outrigger is scanned with alaser beam in a direction that is perpendicularly or oblique (i.e., aflexure width direction) to the arm longitudinal direction. Theoutrigger bends due to the thermal energy of the laser beam. In thismanner, the roll angle and the pitch angle of the suspension can becorrected. Particularly, the laser beam is irradiated on the outriggerfrom a direction approximately perpendicular to a direction of curvatureof the outrigger, moreover, the laser beam is made to enter from one endof the outrigger, scan the outrigger, and go out from the other end ofthe outrigger.

According to the technique disclosed in Japanese Patent ApplicationLaid-open Publication No. H7-77063, a laser beam is irradiated to awidth direction of a spring arm, thereby to correct the load and obtaina prescribed contact pressure. Even in this technique, the laser beam ismade to enter from one end of the spring arm, scan the spring arm, goout from the other end of the spring arm.

Thus, in the conventional approaches, the laser beam is irradiated froma direction that is approximately perpendicularly or oblique to thedirection in which the suspension is curved. As a result, it isdifficult to control bending of the suspension with precision. In otherwords, when the suspension is looked at from a lateral direction, theoutrigger is bent with the laser beam-scanned portion as a fulcrum. As aresult, an error in the position of the scanning is amplified largely atthe end portion of the suspension. Despite the necessity for forming thesuspension in extremely high precision, it is difficult in theconventional approaches to carrying out a fine correction of the load,the roll angle, and the pitch angle of the suspension, or theconventional techniques require correction and inspection to be repeatedmany times. This leads to low productivity.

SUMMARY OF THE INVENTION

It is an object of the present invention to at least solve the problemsin the conventional technology.

The method according to one aspect of the present invention is ofbending a thin plate in a predetermined direction by irradiating a laserbeam onto the thin plate. The method comprises irradiating a laser beamlinearly onto the thin plate in approximately the predetermineddirection.

The method according to another aspect of the present invention is ofbending a thin plate using a laser beam, wherein the laser beam isirradiated onto the thin plate to curve the thin plate.

The method according to still another aspect of the present invention isof correcting a suspension used to mount a magnetic head in a hard diskdrive. The method comprises either one of or both measuring load on thesuspension and obtaining a load adjustment amount from the measuredload; and measuring an angle of the suspension and obtaining an angleadjustment amount from the measured angle; defining, by usingirradiation shapes in advance, that a laser beam is linearly irradiatedonto either one of or both a load curve portion and an angle adjustmentportion of the suspension in approximately the same direction as acurving direction, preparing combinations of irradiation shapes inadvance, and selecting an irradiation shape combination corresponding toeither one of or both the load adjustment amount and the angleadjustment amount; and irradiating a laser beam based on the selectedirradiation shape combination.

The suspension correction method according to still another aspect ofthe present invention is of adjusting an angle of the suspension byirradiating a laser beam onto a laser beam irradiation area forcorrecting an angle in plus or a laser beam irradiation area forcorrecting an angle in minus, based on an arrangement that thesuspension is formed in a thin plate shape as a whole, the header isconnected to an outrigger from one end of a head mounting portion via aspring, and the outrigger consists of a curve portion reaching bothsides of the head mounting portion, and a linear portion that continuesfrom the curve portion, and an XY axis is set around the head mountingportion, an area I to an area IV are formed on the XY coordinates withthe X axis as a gimbal longitudinal direction, and the laser beamirradiation area for correcting the angle in plus or the laser beamirradiation area for correcting the angle in minus is set in the area Iand the area III or the area II and the area IV respectively.

The suspension correction method according to still another aspect ofthe present invention is of adjusting an angle of the suspension byirradiating a laser beam onto a laser beam irradiation area forcorrecting a pitch angle in plus or a laser beam irradiation area forcorrecting a pitch angle in minus, based on an arrangement that thesuspension is formed in a thin plate shape as a whole, the header isconnected to an outrigger from one end of a head mounting portion via aspring, and the outrigger consists of a curve portion reaching bothsides of the head mounting portion, and a linear portion that continuesfrom the curve portion, and a boundary is provided in a directionorthogonal with a gimbal longitudinal direction around the spring, afirst area is formed at the head mounting side, a second area is formedat the opposite side, the laser beam irradiation area for correcting thepitch angle in plus is set in the first area, and the laser beamirradiation area for correcting the pitch angle in minus is set in thesecond area.

The thin plate according to still another aspect of the presentinvention has at least one portion thereof formed in a curve and beamshape, and has a laser beam irradiation trajectory linearly formed inapproximately the same direction as the curve direction.

The apparatus for correcting a suspension used to mount a magnetic headin a hard disk drive according to still another aspect of the presentinvention comprises either one of or both a load measuring unit thatmeasures a load on the suspension; and an angle measuring unit thatmeasures an angle of the suspension; a laser beam irradiating unit thatirradiates a laser beam in approximately the same direction as a curvingdirection onto either one of or both load correction area and an anglecorrection area of the suspension, based on either one of or both theload measured by the load measuring unit and the angle measured by theangle measuring unit; and a conveyer unit that fixes the suspension ontoa conveyer stage, and conveys the suspension while positioning thesuspension on either one of or both the load measuring unit and theangle measuring unit, and the laser beam irradiating unit.

The computer program that makes a computer according to still anotheraspect of the present invention executes either one of or both defining,by using irradiation shapes in advance, that a laser beam is linearlyirradiated onto any one part of a load curve portion of a suspension inapproximately the same direction as a curving direction, and preparingcombinations of irradiation shapes in advance; and defining, by usingirradiation shapes in advance, that a laser beam is linearly irradiatedonto any one part of an angle adjustment portion of a suspension inapproximately the same direction as a curving direction, and preparingcombinations of irradiation shapes in advance; and a selecting step ofselecting an irradiation shape combination corresponding to either oneof or both the load adjustment amount and the angle adjustment amountobtained from a measured load of a head of a hard disk drive thatpresses against a disk in the hard disk drive, and using the selectedcombination to irradiate the laser beam.

The other objects, features and advantages of the present invention arespecifically set forth in or will become apparent from the followingdetailed descriptions of the invention when read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structure diagram of a suspension correction apparatusaccording to a first embodiment of the present invention;

FIG. 2 is a block diagram of a structure of the suspension correctionapparatus shown in FIG. 1;

FIG. 3 is an explanatory view of a suspension fixed to a correctionapparatus;

FIG. 4 is a perspective view of one example of a suspension to becorrected by the suspension correction apparatus shown in FIG. 1 or FIG.2;

FIG. 5 is an explanatory view of a laser beam irradiation area on a loadcurve portion of a suspension;

FIG. 6 is an explanatory view of a laser beam irradiation area on anangle adjustment portion of a suspension;

FIG. 7 is an explanatory view of a laser beam irradiation area on anangle adjustment portion of a suspension according to anotherembodiment;

FIG. 8 is an explanatory view of one example of a character when a laserbeam irradiation shape is registered as a character;

FIG. 9 is a flowchart of a suspension correction process;

FIGS. 10A and 10B are comparative explanatory views of curved states ofa load curve portion and an angle-adjusted portion respectively;

FIG. 11 is an explanatory view of one example of a relationship betweena wiring area and a laser beam irradiation area;

FIG. 12 is an explanatory view of another example of a relationshipbetween a wiring area and a laser beam irradiation area;

FIG. 13 is an explanatory view of still another example of arelationship between a wiring area and a laser beam irradiation area;

FIG. 14 is an explanatory view of still another example of arelationship between a wiring area and a laser beam irradiation area;

FIG. 15 is a structure diagram of a suspension correction apparatusaccording to the second embodiment of the present invention;

FIG. 16 is a structure diagram of a modification of the suspensioncorrection apparatus shown in FIG. 14; and

FIG. 17 is an explanatory view of a layout of a laser beam irradiationarea.

DETAILED DESCRIPTION

Exemplary embodiments of to the present invention will be explained indetail below with reference to the accompanying drawings. However, thepresent invention is not limited to these embodiments. Constituentelements in the embodiments include those which a person skilled in theart could easily conceive, or those which are substantially identical toeach other.

FIG. 1 is a structure diagram of a suspension correction apparatus 100according to a first embodiment of the present invention. FIG. 2 is ablock diagram of the suspension correction apparatus 100. FIG. 3 is anexplanatory view of a suspension fixed to the suspension correctionapparatus 100.

The suspension correction apparatus 100 has a load measuring unit 1, anangle measuring unit 2, a laser marker 3, a conveyer 4 that conveyssuspensions 200, a computer 5 for control, and a laser marker main body6. Although the laser marker 3 is preferable, any other means that canirradiate a laser beam is sufficient.

The suspensions 200 are provisionally fixed at an appropriate distanceonto a conveyer stage 7 of the conveyer 4. The conveyer 4 is moved sothat one suspension 200 is positioned beneath the load measuring unit 1,the angle measuring unit 2, and the laser marker 3 respectively. Aservomotor 8, a ball screw 9, and a direct-acting guide 10 control themove of the conveyer stage 7. To fix the suspension 200 onto theconveyer stage 7, the suspension 200 is sandwiched between a tool 11(see FIG. 3) and the conveyer stage 7, for example. Other means such asan absorber, a bolt, a magnet, for example, may be used instead of thetool 11. Controllers (not shown) for the conveyer stage 7 and the tool11 are respectively connected to the computer 5. The computer carriesout the entire control.

The load measuring unit 1 consists of a probe 12 that presses a specificportion of the suspension 200, and a load cell 13 provided on the probe12. The probe 12 is moved up and down with a combination of a servomotor 14 or a stepping motor having a direct-acting guide, and a ball15, or with an up-and-down moving actuator consisting of a hydrauliccylinder not shown. A front end 12 a of the probe 12 is approximatelyspherical, and is pressed against a magnetic head mounting portion ofthe suspension 200. The pressure exerted by the probe 12 on thesuspension is constant, and an output signal (i.e., voltage) from a loadcell 13 is sent to the computer 5. The computer 5 estimates the load onthe suspension 200 based on the signal from the load cell 13.

The angle measuring unit 2 consists of a laser beam source 16 thatirradiates a laser beam onto a magnetic head mounting portion of thesuspension 200, and a light receiver 19. The light receiver 19 includesa charge-coupled device (CCD) 17 and an amplifier (AMP) 18. The CCD 17sends a signal to the computer 5, via the amplifier 18. The computerestimates an angle of curvature of the suspension 200 at a position of areflection beam of the laser beam. The load measuring unit 1 and theangle measuring unit 2 are located at the upstream of the correctionprocess of the laser marker 3.

A general laser marker irradiates a laser beam onto a work piece tovaporize, modify or discolor the workpiece surface according toabsorption fever, thereby to differentiate between the appearance of thelaser beam-irradiated portion and the appearance of a laser beamnon-irradiated portion. According to the present invention, as the lasermarker 3 is used, it is preferable to use the original application ofthe marker, although the application is not limited to this method. Inother words, it is sufficient to register in advance a laser beamirradiation shape such as a character as a mark (i.e., font) on thesuspension 200. When the workpiece surface is processed while feeding itat a predetermined pitch like a usual mark (for example, when acharacter is formed at a predetermined pitch to write a sentence), it isnot possible to irradiate a laser beam using a combination of aplurality of irradiation shapes. Therefore, a laser beam is irradiatedin a state of a pitch “0”.

The laser marker 3 consists of a laser marker head 20, and the lasermarker main body 6 that is connected to the laser marker head 20 via anoptical fiber 21. A laser beam emitted from the main body of the lasermarker 3 is transmitted through the optical fiber 21, and is irradiatedfrom the laser marker head 20 to the suspension 200. The laser markerhead 20 polarizes the laser beam with a galvano scanner mirror 22 in theXY directions, and irradiates an energy-condensed laser beam to thesuspension 200 with a condenser 23.

The laser marker main body 6 incorporates a laser oscillator 24 and acontroller 25. The laser oscillator 24 emits a laser beam by exciting anoscillation medium, such as a YAG laser, for example, with a flash lampor a laser diode (LD). The controller 25 controls the laser marker head20 to irradiate the laser beam onto a specific position by synchronizingthe laser oscillation with the mirror driving. Particularly, the laserdiameter can be made small by using a single mode laser, and therefore,it is possible to securely irradiate a narrow portion between wires asdescribed later. When a laser beam from a galvano head is condensed witha long focal length lens thereby to obtain a deep depth of focus, theenergy density of the laser beam changes little even when a distancebetween the laser marker head 20 and the suspension 200 changes.Therefore, it is not necessary to fine-control the focal length.

The computer 5 has a load set value memory 51 that stores a load setvalue required for the suspension 200, a load adjustment amountcalculator 52 that calculates a load adjustment amount by comparing theoutput signal from the load measuring unit 1 with the load set value, aload database 53 that stores combinations of load characters (i.e.,irradiation shapes) corresponding to each load, and a load charactercombination selector 54 that selects a specific combination of loadcharacters from among the combinations of the load characters to correctload to a proper value.

The computer 5 further has an angle set value memory 55 that stores anangle set value required for the suspension 200, an angle adjustmentamount calculator 56 that calculates an angle adjustment amount bycomparing the output signal from the angle measuring unit 2 with theangle set value, an angle database 57 that stores combinations of anglecharacters (i.e., irradiation shapes) corresponding to each angle, andan angle character combination selector 58 that selects a specificcombination of angle characters from among the combinations of the anglecharacters to correct an angle to a proper value. The computer 5 furtherhas an adder 59 that adds a load character selected by the loadcharacter combination selector 54, and an angle character selected bythe angle character combination selector 58. The computer 5 realizes thefunctions of these sections with hardware including a CPU of thecomputer, memories, etc., and predetermined software.

The controller 25 of the laser marker main body 6 has a character setcode memory 61 that stores a character set code, a character converter62 that decodes a character by referring to a character set code, andconverts the character into shape information, and a laser beamirradiation position converter 63 that converts the information aboutthe converted shape into a positional shape to be actually irradiatedwith a laser beam. The character converter 62 and the laser beamirradiation position converter 63 can be structured to have similarfunctions according to a general-purpose computer and predeterminedsoftware.

FIG. 4 is a perspective view of one example of the suspension 200. Thissuspension 200 has a load beam 203 provided on a base plate 201 via aload curve portion 202. A flexure 204 is spot welded on a front end ofthe load beam 203 via a load arm fitter 207 (see FIG. 5). The flexure204 includes a gimbal spring 205 (see FIG. 6), outriggers 206 and 206,and a magnetic head mounting portion 208. The magnetic head mountingportion 208 is in contact with a dimple 208 a formed on the front end ofthe load beam. The dimple 208 a is positioned at approximately thecenter of the head when the head is mounted.

The flexure 204 is formed by etching or punching a stainless plate in apredetermined shape. A slider 209 for flying is provided on the magnetichead mounting portion 208, with a magnetic head 210 provided on the endof the slider 209, as indicated by a dotted line in the drawing. Thebase plate 201 and the load beam 203 need not be formed integrally, butmay have a structure having separate members spot welded. In this case,the load beam 203 and the load curve portion 202 are integrated, and apart of or the whole load curve portion 202 can be structured to have asmall plate thickness by partial etching or the like. Alternatively, theload curve portion 202 as a separate unit may be fixed to the load beam203 in a hinged shape. The load curve portion 202 may be fixed to thebase plate 201 by spot welding.

The load curve portion 202 is curved in a pitch direction in advance bypressing or the like to obtain proper load on the head mounting portion208. As the suspension 200 is mechanically curved as described above,the load needs to be corrected so that it is properly applied to thehead mounting portion 208. The angle of the head mounting portion 208also needs to be corrected to obtain a proper angle relative to a diskin the hard disk drive.

FIG. 5 is an explanatory view of a laser beam irradiation area on theload curve portion of the suspension, and FIG. 6 is an explanatory viewof the laser beam irradiation area on the angle adjustment portion ofthe suspension. The load curve portion 202 is positioned to stridebetween the base plate 201 and the load beam 203 with two legs, and isformed thin when necessary. A plurality of laser beam irradiation areas211 are linearly provided in a curved direction of the load curveportion 202 (i.e., a direction perpendicular to a bent or curved edgeline when curved). The laser beam irradiation areas 211 mean ranges inwhich a laser beam can be irradiated. A length and a shape of anirradiation beam are determined within each range as described later. Alaser beam is irradiated to the whole or a part of the laser beamirradiation areas 211. A first point F and an end point E of each laserbeam irradiation area 211 are accommodated within the load curve portion202. Only one of the first point F and the end point E may beaccommodated within the load curve portion 202. Irradiation of laserbeams having four kinds of length, for example, is scheduled in thelaser beam irradiation areas 211 within the load curve portion 202. Inthis case, a suitable length is selected according to a correction level(i.e., a load adjustment amount). The laser beam irradiation areas 211are symmetrically corrected by curving the suspension 200 in the pitchdirection. Although the load curve portion 202 is defined as the laserbeam irradiation areas 211, a shape indicated in the drawing is notactually marked in the load curve portion 202. Only the execution of thecorrection within the correction apparatus 100 is defined.

As shown in FIG. 6, a plurality of laser beam irradiation areas 213 and214 of an angle adjustment portion 212 are set in the outriggers 206 ofthe flexure 204. Specifically, the laser beam irradiation areas 213 and214 are set on linear portions 206 a each extending from a root portion204 a of the outrigger 206, and on curve portions 206 b each extendingfrom the linear portion 206 a to the gimbal spring 205. Similarly, theselaser beam irradiation areas 213 and 214 are defined as the angleadjustment portion 212 within the correction apparatus 100, and amarking is not particularly provided. A marking may be provided to allowvisual recognition of the laser beam irradiation areas 211, 213, and214.

The magnetic head mounting portion takes the coordinate XY axis aroundthe center of (in general, a position of the dimple 208 a). In thiscase, when a laser beam is irradiated onto a range I and a range III ofthe outriggers, the roll angle is corrected in minus. When a laser beamis irradiated onto laser beam irradiation areas of a range II and arange IV of the outriggers, the roll angle is corrected in plus. When alaser beam is irradiated onto a laser beam irradiation area of an area V(i.e., a first area), with the center of the gimbal spring 205 as aboundary, the pitch angle is corrected in plus. When a laser beam isirradiated onto a laser beam irradiation range of an area VI (i.e., asecond area), the pitch angle is corrected in minus. Therefore, althoughit is not possible to correct the pitch angle and the roll angleindividually, the roll angle and the pitch angle can be properlycorrected when they are combined together.

The suspensions 200 shown in FIG. 4 to FIG. 6 are one example, and it isneedless to mention that the laser beam irradiation areas can beprovided at portions that rule the load and the angle of the suspensionhaving other shapes. The shapes of the laser beam irradiation areas aredetermined according to various conditions such as shapes and materialsof the suspensions. Therefore, it is not possible to uniquely determineshapes of all the suspensions. Shapes and positions of the laser beamirradiation areas can be set based on experience or by simulation usinga computer.

A first point F and an end point E of each of the laser beam irradiationareas 213 and 214 are accommodated within the angle adjustment portion212. Only one of the first point F and the end point E may beaccommodated within the angle adjustment portion 212. As shown in FIG.6, the laser beam irradiation areas 213 and 214 are set so that they arenot superimposed with a wiring area 215 a that is located between theoutrigger 206 and the magnetic head mounting portion 208. A wiringportion such as a flexible substrate including a patterned copper andinsulation layer is disposed in the wiring area 215 a, and is actuallybuoyant from the outrigger 206.

The irradiation of a laser beam onto the wiring area 215 a has a risk ofan occurrence of a disconnection or a wiring failure due to an excessivethermal load on the wire. This also has a risk of burning the flexiblesubstrate. When the laser beam irradiation areas 213 and 214 are setkeeping out of the wiring area 215 a as shown in the drawing, a laserbeam is not irradiated onto the wiring area 215 a. Therefore, this hasan advantage that no inconvenience occurs due to the laser beam. Asshown in FIG. 7, depending on the structure, an insulation layer isformed along a longitudinal direction of the outriggers 206 and 206 onthe stainless surface of the flexure 204, and a conductor is formed onthe insulation layer. This structure also has a problem of an excessivethermal load on the wire. Therefore, it is preferable to set the laserbeam irradiation areas 213 and 214 by keeping out of the wiring area 215a as shown in the drawing.

In the present invention, a laser beam is irradiated onto apredetermined portion of the suspension 200, thereby to correct the loadand angle by utilizing the thermal deformation. Therefore, it isnecessary to acquire in advance thermal deformation due to the laserbeam for each of the laser beam irradiation areas 211, 213, and 214. Forexample, when a laser beam of a predetermined shape and a predeterminedlength is irradiated onto the laser beam irradiation areas 211, 213, and214 shown in FIG. 5 and FIG. 6, the displacement of the load curveportion 202 and the angle adjustment portion 212 changes due to theirradiation of the laser beam. This relationship needs to be obtained byexperiment or by simulation, and stored in a database. A detailedexample of the database is built into the computer 5 shown in FIG. 2. Anirradiation shape of the laser beam to carry out a correction based onthe load adjustment amount and the angle adjustment amount is registeredas a character in the database.

FIG. 8 is an explanatory view of one example of a character when a laserbeam irradiation shape is registered as a character. A character of acode C1 represents a laser beam irradiation shape (i.e., the alphabet)that is used when the laser marker 3 is usually used. A code C2 to acode C11 represent characters that are used to correct the suspension bya predetermined load adjustment amount. For example, the character ofthe code C2 is used to irradiate a laser beam onto a lower left positionwithin a frame of a predetermined size (i.e., laser beam irradiationrange). The character of the code C3 is used to irradiate a laser beamonto an upper left position within a frame. The characters of the codeC4 to a code C11 are similarly used to irradiate a laser beam ontopredetermined positions respectively.

Each of a code C12 to a code C15 represents a combination of characters.For example, the code C12 is a combination of the character 1 and thecharacter 4. The character C12 makes it possible to correct thesuspension by a predetermined load adjustment amount or a predeterminedangle adjustment amount based on this combination. The code C13 and thecode C15 similarly represent combinations of predetermined charactersrespectively. Based on these combinations, it becomes possible tocorrect the suspension by a predetermined load adjustment amount or apredetermined angle adjustment amount. Actually, combinations of aplurality of kinds of characters are prepared to cover the whole rangeof requested load adjustment amounts and angle adjustment amounts, andthese character combinations are stored in the load database or theangle database. The suspension is corrected based on these charactercombinations because the correction of a roll angle (or a pitch angle)using each character substantially unavoidably affects the pitch angle(or the roll angle), making it impossible to individually correct theroll angle or the pitch angle. For this reason, it is necessary to usecombinations of a plurality of characters to carry out the correction,thereby to generate optimum characters.

The character combinations are coded and stored in the load database 53and the angle database 57 respectively. The load character combinationselector 54 and the angle character combination selector 58 select thesecharacter combinations to adjust the load and the angle respectively.The adder 59 adds character codes, and the character converter 62converts the added character codes into position data by referring tothe character set code. The laser beam irradiation position converter 63converts the position data into irradiation position data to irradiate alaser beam.

FIG. 9 is a flowchart of a suspension correction process. First, thesuspension 200 is held on the conveyer stage 7, and the conveyer stage 7is moved by a predetermined distance to position the suspension 200beneath the load measuring unit 1 (step S1). The load measuring unit 1lowers the probe 12 to press the front end 12 a of the probe 12 againstthe magnetic head mounting portion 208, and further pushes the front end12 a into the magnetic head mounting portion 208 by a predeterminedamount. The load measuring apparatus 1 measures, with the load cell 13,the load applied to the suspension 200 (step S2) and outputs a signalcorresponding to the result of the measurement.

The computer 5 receives the signal from the load cell 13. The loadadjustment amount calculator 52 in the computer 5 compares this loadwith a load set value stored in the load set value memory 51, anddetermines a load (hereinafter, “load adjustment amount”) to adjust theload (step S3). The conveyer stage 7 is moved to position the suspension200 beneath the angle measurer 2 (step S4). A laser beam is irradiatedonto the magnetic head mounting portion 208 of the suspension 200. TheCCD 17 receives a laser beam that is reflected from the suspension 200.The CCD 17 outputs a signal corresponding to amount of received light.The computer 5 receives the signal and estimates an actual angle of thecurvature (step S5).

The angle adjustment amount calculator 56 in the computer 5 compares theangle with an angle set value stored in the angle set value memory 55,and determines an angle (hereinafter, “angle adjustment amount”) toadjust the angle (step S6). The load character combination selector 54selects a plurality of load characters stored in the load database 53according to the load adjustment amount. Further, the angle charactercombination selector 58 selects a plurality of angle characters storedin the angle database 57 according to the angle adjustment amount (stepS7). The adder 59 adds the load character selected by the load charactercombination selector 54 and the angle selected by the angle charactercombination selector 58. In other words, the adder 59 generates acharacter code to be used to finally correct both the roll angle and thepitch angle of the suspension 200 (step S8). The character combinationsare as exemplified in FIG. 8.

The computer 5 sends the character code to the laser marker 3. Thecharacter converter 62 of the laser marker 3 converts the character codeinto a character by referring to the code stored in the character setcode memory 61 (step S9). The laser beam irradiation position converter63 converts the converted character into laser beam irradiation positiondata (step S10). A laser output amount is selected from the database(step S11), and a laser beam defocus amount is selected from thedatabase (step S12). The laser marker main body 6 drives the lasermarker head 20 based on the laser beam irradiation position data, andirradiates a laser beam onto the load curve portion 202 and the angleadjustment portion 212 of the suspension 200 respectively (step S13).The combined characters are sequentially irradiated. As the transmissionpitch is “0”, substantially a laser beam of the combined shape of thecharacters is irradiated.

Referring back to FIG. 5 and FIG. 6, the actual laser beam irradiationcondition can be understood by experiment. For example, the load changeamount in the load curve portion 202 of the suspension shown in FIG. 5is proportional to a scan length and a number of laser beams. A scanlength and a number of irradiation laser beams are defined for each loadcharacter combination. A corresponding combination is selected fromamong necessary load adjustment amounts. The laser beam is irradiatedaccordingly, which makes it possible to carry out a fast loadadjustment. This similarly applies to the angle change amount in theangle adjustment portion shown in FIG. 6. Each angle charactercombination is proportional to a scan length and a number of laserbeams. A corresponding combination of angle characters is selected fromamong necessary angle adjustment amounts. The laser beam is irradiatedaccordingly.

A laser beam of a predetermined length and a predetermined shape isirradiated onto the laser beam irradiation areas 211, 213, and 214 ofthe load curve portion 202 and the angle adjustment portion 212respectively. With this arrangement, a laser beam irradiation areaincluding its surrounding is curved as shown in FIG. 10A. In the case ofthe load curve portion 202 shown in FIG. 5, for example, the laser beamirradiation area is curved at a predetermined curvature in approximatelya perpendicular direction with respect to the paper surface. As aresult, a portion that is actually irradiated with the laser beam in thelaser beam irradiation area 211 is curved as an arc. The laser beamirradiation portion of the angle adjustment portion 212 shown in FIG. 6is also curved. On the other hand, according to the conventional methodof correcting load and an angle, a laser beam is irradiatedapproximately perpendicularly or in slanting relative to the curvedeformation direction. Therefore, as shown in FIG. 10B, a suspension 900is bent at an angle formed by a laser beam scanning line 901, whichinvolves difficulty in high-precision adjustment. As explained above, byscanning the suspension with a laser beam along a direction of a curvedeformation, the suspension can be curved in high precision. Further,according to the conventional method, stress is concentrated onto alaser beam scanning line 901, which involves a risk of breaking thesuspension. However, according to the present invention, as the laserbeam irradiation portion is curved, the stress concentration due to thisdeformation is prevented, resulting in no breaking of the suspension.Further, as a laser beam is not irradiated onto the edge portion, theheat of the laser beam is spread to the surrounding. Therefore, it ispossible to prevent the occurrence of browning. On the other hand,according to the conventional method, the laser beam scanning line 901passes through the edge of the load curve portion 202 and the angleadjustment portion 212. As the edge portion has little spread area ofthe laser beam, browning occurs relatively easily.

As shown in FIG. 5 and FIG. 6, the scanning first point F and the endpoint E of the laser beam are positioned at optional points of thesuspension 200. Therefore, the thermo-mechanical treatment heat spreadsto the vicinity of the irradiation surface at the first point F and theend point E. Consequently, there occurs no inconvenience of discoloringor browning in the vicinity of the end portion of the suspension 200. Asthe laser beam irradiation length can be set to an optional level, it ispossible to realize fast high-precision processing by dividing the areaof the irradiation position. For example, in FIG. 5, out of ten laserbeam irradiation areas 211, internal eight areas are used as coarseadjustment areas, and external two areas are used as fine adjustmentareas. In other words, the areas are divided into the coarse adjustmentareas and the fine adjustment areas. For example, a high-energy laserbeam is fast irradiated onto the coarse adjustment areas, and arelatively low-energy laser beam is accurately irradiated onto the fineadjustment areas. With this arrangement, fast and fine adjustmentprocessing can be carried out in total.

The laser marker head 20 focuses the laser beam from the galvano headwith the long focal length lens thereby to obtain a deep depth of focus.Therefore, a change in the energy density of the laser beam can besuppressed even when a distance between the laser marker head 20 and thesuspension 200 changes. Accordingly, a fine active control of the focallength of the suspension 200 becomes unnecessary, or a relatively coarsecontrol is sufficient. As a result, the correction apparatus can bestructured at low cost. Further, this does not cause the occurrence ofinconvenience such as browning due to the excessive energyconcentration.

The condenser 23 or the like defocuses the diameter of the laser beam tosome extent to adjust the energy density of the laser beam. With thisarrangement, a laser beam irradiation damage can be reduced, and theprocessing speed can be improved. A defocusing level can be suitablydetermined according to a material and a thickness of the suspension ora laser beam irradiation position. In short, the diameter of the laserbeam can be adjusted to such an extent that a laser beam damage such asbrowning does not occur. It is extremely effective to reduce the laserbeam damage when both of the following conditions are satisfied; makinga laser beam diameter approximately constant by obtaining a deeper depthof focus with the long focal length lens, and obtaining a relativelylarge laser beam diameter by defocusing.

When a laser beam is irradiated onto the surrounding of the wiring orbetween the wires after making small the diameter of the laser beam tobe irradiated onto the laser beam irradiation areas 211, 213, and 214,the wires are not badly affected by browning or the like. FIG. 11 is anexplanatory view of one example of a relationship between a wiring area215 and the laser beam irradiation area 213. As shown in FIG. 11, thewiring area 215 is formed on the outrigger 206 of the flexure 204. Alaser beam irradiation area 213 a is set approximately in parallel witha wire 215 a and a wire 215 b between these wires. When necessary, alaser beam irradiation area 213 b is set between the wire 215 b and theend of the outrigger 206. With this arrangement, a laser beam is notirradiated onto the wiring area 215, which prevents the occurrence ofbrowning or a disconnection of the wires 215 a and 215 b.

Further, as shown in FIG. 12, when the wiring area 215 is present in thelinear portion 206 a of the outrigger 206 of the flexure 204 and in acurve portion 206 b (i.e., the angle adjustment portion 212) reachingfrom the linear portion 206 a to the gimbal spring 205, the laser beamirradiation area 214 may be set along the wire 215 a and the wire 215 bbetween these wires. From the other viewpoint, when the laser beam isirradiated, the heat of the laser beam is transmitted to the wiring area215, particularly because the suspension 200 is made of metal. In thiscase, the wiring area 215 needs to be separated from the laser beamirradiation areas 213 and 214 to such an extent that this thermalinfluence does not become a problem. The isolation distance may bedetermined by experiment or by simulation. When the laser beamirradiation position is deviated due to a shortage of alignment or thelike, this may damage the wires. In this case, it is preferable to setthe laser beam irradiation areas 213 and 214 by taking this deviationinto account.

Further, from the other viewpoint, it is possible to prevent the wiresfrom being badly affected, by setting the laser beam irradiation areas213 and 214 along the wiring area 215. Further, from the otherviewpoint, the laser beam irradiation areas 213 and 214 can be setkeeping out of the wiring area 215. These positional relationshipsbetween the wiring area and the laser beam irradiation areas can also beapplied in a similar manner to other structures than those shown inFIGS. 5, 6, 10, and 11.

Further, as shown in FIG. 13, laser beam irradiation areas 216 may beset linearly at a constant interval, and a laser beam is irradiated ontothese laser beam irradiation areas 216. As a result of the linearirradiation of the laser beam, the load curve portion 202 and the angleadjustment portion 212 are curved approximately in the same manner asthat shown in FIG. 10A. In other words, in the present invention, inorder to carry out a curve correction in high precision, the laser beamirradiation areas need not be continuous straight lines, and may besubstantially linear as shown in FIG. 13. In linearly irradiating alaser beam, the laser beam may be irradiated in a scatter within a laserbeam irradiation area set in advance. Alternatively, the laser beam maybe irradiated in a wave shape within a laser beam irradiation area setin advance.

A curve shape may be fine controlled by changing the energy of the laserbeam during a laser beam scanning. For example, as shown in FIG. 14, thediameter of the laser beam may be changed by controlling the focus ofthe laser beam, thereby to change the irradiation width of the laserbeam to be irradiated onto the outrigger 206 (corresponding to the laserbeam irradiation area 217). With this arrangement, the curvature of aportion 217 a having a large irradiation width can be made large, andthe curvature of a portion 217 b having a small irradiation width can bemade small. By differentiating between these curvatures, a finer curvingcan be achieved. Further, the energy density of the laser beam may bechanged without changing the laser beam diameter, thereby to adjust theoutput. With this arrangement, as the energy is not concentrated to onepoint, and the output can be changed in a predetermined laser beamdiameter, browning does not occur.

According to the suspension correction apparatus 100, the load measuringunit 1 and the angle measuring unit 2 measure the load and the angle ofthe suspension 200 respectively at the upstream of the correctionprocess, as shown in FIG. 1. In order to measure the load and the angleafter the correction, the load measuring unit 1 and the angle measuringunit 2 may be further provided at the downstream of the laser markerhead 20 (not shown). The load measuring unit 1 and the angle measuringunit 2 disposed at the downstream can decide whether the correction iscarried out properly. When the correction is not sufficient, the loadand the angle may be measured again. In the structure shown in FIG. 1,the conveyer stage 7 may be returned to the reverse direction after thecorrection, and the load measuring unit 1 and the angle measuring unit 2disposed at the upstream can measure the load the angle again.

FIG. 15 is a structure diagram of a suspension correction apparatus 300according to a second embodiment of the present invention. Thesuspension correction apparatus 300 has laser marker heads 20 and 301disposed both above and below the suspension 200 respectively, withother structures remain unchanged from those of the suspensioncorrection apparatus 100 according to the first embodiment. Therefore,the explanation of the other structures is omitted. As described above,when the laser beam is irradiated onto the load curve portion 202 andthe angle adjustment portion 212 of the suspension 200 respectively, thecurve deformation portion may be excessively corrected depending on theirradiation state of the laser beam. In this case, the second lasermarker head 301 disposed opposite to the first laser marker head 20irradiates the laser beam onto the opposite surface of the load curveportion 202 and the angle adjustment portion 212 respectively. With thisarrangement, the load curve portion 202 and the angle adjustment portion212 are curved in a direction opposite to the once curved direction.This negative correction cancels the excessive correction. When thelaser beam is irradiated onto the opposite surface, the correction rangecan be enlarged as compared with when the laser beam is irradiated fromonly one direction.

The second laser marker may be located at the same side as the firstlaser marker head, instead of at the opposite side. After the firstlaser marker head irradiates, the suspension is vertically inverted, andthen the second laser marker head irradiates (not shown). Alternatively,the first laser marker head first irradiates, and the suspensionvertically inverts and is conveyed to the position of the first lasermarker head again. Then, the first laser marker head irradiates. In thiscase, the second laser marker is not necessary.

Instead of using the two laser marker heads as described above, onelaser marker head 20 may be used as exemplified by a modification inFIG. 16. A reflection mirror 302 is provided at the opposite side of thesuspension 200, thereby to reflect the laser beam from the laser markerhead 20, and irradiate the laser beam to the rear surface of the loadcurve portion 202 and the angle adjustment portion 212 respectively.While the laser marker head 20 can preferably carry out the laserscanning, the reflection mirror 302 may carry out the scanning instead.

The load curve portion 202 and the angle adjustment portion 212 areformed with thin plates. Therefore, when a laser beam is irradiated ontothe same position on both sides of the load curve portion 202 and theangle adjustment portion 212 respectively, curve deformation may not beachieved as expected because of superimposition of thermally influencedportions of the material. In this case, as shown in FIG. 17, it ispreferable that laser beam irradiation areas are set at differentpositions of both sides of the load curve portion 202 and the angleadjustment portion 212 respectively. A solid line represents a laserbeam irradiation area 218 on the front surface, and a dotted linerepresents a laser beam irradiation area 219 on the rear surface.

While the suspension is explained as the object to be corrected by thesuspension correction apparatus in the above, it is needless to mentionthat the suspension correction apparatus can correct other objects aswell. Specifically, the suspension correction apparatus can preferablycorrect an object that requires a fine correction of both or either oneof a pitch angle and a roll angle. For example, the suspensioncorrection apparatus can correct an optical axis of a cantilever probeof an atomic force microscope that uses a metal plate, an optical headand optical communication connector, a micro contactor, etc.

In the first and second embodiments, the laser marker 3 is used to carryout the laser beam irradiation. However, when this character isprogrammed, it is not necessary to use the commercially available lasermarker 3.

While the load adjustment and the angle adjustment are carried out atthe same time in the above embodiments, only one of these adjustmentsmay be carried out. In this case, a character combination may beselected based on the obtained load adjustment amount or angleadjustment amount.

As explained above, according to one aspect of the present invention,the thin plate formation method makes it possible to achieve a finecurve formation. This method also makes it possible to adjust the loadof the suspension easily and in high precision.

According to another aspect of the present invention, the thin platebecomes a proper product that is curved in high precision. According tostill another aspect of the present invention, the suspension correctionapparatus can fine control the load and the angle of the suspension.

According to still another aspect of the present invention, thesuspension correction apparatus can irradiate a laser beam of a specificirradiation shape onto the suspension relatively easily. According tostill another aspect of the pre sent invention, the suspensioncorrection apparatus has two separate laser beam irradiating unitsprovided to sandwich the suspension. Therefore, the correction range canbe enlarged.

Although the invention has been described with respect to a specificembodiment for a complete and clear disclosure, the appended claims arenot to be thus limited but are to be construed as embodying allmodifications and alternative constructions that may occur to oneskilled in the art which fairly fall within the basic teaching hereinset forth.

1. A method of correcting a suspension used to mount a magnetic head ina hard disk drive, comprising: measuring a load applied to thesuspension, comparing the measured load with a stored load set value,and obtaining a load adjustment amount; and measuring an angle of thesuspension, comparing the measured angle with a stored angle set value,and obtaining an angle adjustment amount; defining, by using pre-storedirradiation shapes, that a laser beam is linearly irradiated onto eitherone of or both a load curve portion and an angle adjustment portion ofthe suspension in a laser beam irradiation area between a first pointand an end point in approximately the same direction as a curvingdirection, preparing combinations of pre-stored irradiation shapes, andselecting an irradiation shape combination corresponding to both theload adjustment amount and the angle adjustment amount; and irradiatinga laser beam based on the selected irradiation shape combination tocurve the thin plate between the first point and the end point, whereinthe laser beam is polarized in XY directions with a galvano scannermirror and is condensed with a long focal length lens.